Many printers, including many inkjet printers, use a carriage-based architecture, which has advantages in size, performance, and cost. In the inkjet carriage printer, a printhead is mounted in a carriage that is moved back and forth across the region of printing. To print an image on a sheet of paper or other recording medium (sometimes generically referred to as paper herein), the recording medium is advanced a given distance along a recording medium advance direction and then momentarily stopped. While the recording medium is stopped and supported on a platen, the printhead carriage is moved along a carriage scan direction. The carriage scan direction extends substantially perpendicular to the recording medium advance direction. In the course of printhead travel along the carriage scan direction, controllable marking elements in the printhead record marks on the recording medium—for example by ejecting drops from an inkjet printhead. After the carriage has printed a swath of the image while traversing the recording medium, the recording medium is advanced incrementally, the carriage direction of motion is reversed, and marking is repeated with printhead movement in the reverse direction. By repeating this process a number of times, the printer forms the image onto the recording medium, swath by swath.
By way of example, FIG. 1 shows a portion of a prior art carriage printer 300, with some parts hidden so that other parts can be more clearly seen. Printer 300 has a printing region 303 across which a carriage 200 is moved back and forth along a carriage scan direction 305 that extends along the X axis between the right side 306 and the left side 307 of printer 300 while printing on recording medium that is supported by the platen that provides printing region 303. Carriage motor 380 moves a belt 384 attached to carriage 200 in order to move carriage 200 back and forth along carriage guide rail 382. In this way, carriage 200 is actuable to move along a carriage scan direction 305. Printhead 250 is mounted in carriage 200, and ink supplies 262 and 264 are mounted in the printhead 250. In this orientation of printhead 250, the droplets of ink are ejected downward onto the recording media in printing region 303 in the view of FIG. 1, Ink supply 262, in this example, contains five ink sources cyan, magenta, yellow, photo black, and colorless protective fluid, while ink supply 264 contains the ink source for text black.
Toward the left side 307 in the example of FIG. 1 is a maintenance station 330. Toward the rear 309 of the printer in this example is located an electronics board 390, which contains cable connectors 392 for communicating via cables (not shown) to the printhead carriage 200 and from there to the printhead. Also on the electronics board are typically mounted motor controllers for the carriage motor 380 and for the paper advance motor, a processor and/or other control electronics for controlling the printing process, and an optional connector for a cable to a host computer.
Paper, or other recording medium is loaded along paper load entry direction 302 toward the front 308 of printer 300. Printed paper traveling from the rear 309 exits along direction 304. In this example, both the paper load entry direction 302 and the paper exit direction 304 are parallel to the Y axis. A feed roller 312 includes a feed roller shaft along its axis, and a feed roller gear 311 is mounted on the feed roller shaft. The motor that powers the paper advance rollers is not shown in FIG. 1, but a hole 310 in the framework at the right side 306 of the printer 300 is where the motor-gear (not shown) protrudes through in order to engage feed roller gear 311, as well as the gear for the discharge roller (not shown). Bolt holes for attaching this paper advance motor are shown on both sides of hole 310. For normal paper pick-up and feeding, all rollers rotate in forward direction 313. The motor that powers the paper advance rollers provides power directly to the teed roller and the discharge roller, but also provides power indirectly to a pick-up roller and a turn roller (not shown in FIG. 1) that respectively pick up a sheet of recording medium from the paper load entry region, and turn the direction of paper from entry direction 302 to exit direction 304. In conventional printers, power is transmitted from the feed roller 312 to respective gear trains to power the pick-up roller and the turn roller. Such gear trains work well, but a gear train having many gears tends to add to both the expense and the noise of the printing apparatus.
What is needed is a paper feeding apparatus that transmits power from the feed roller to another roller assembly in the printer in a quieter way and for less expense than is associated with the conventional gear train.